Coking method



Sept. 29, 1964 HEINZE ETAL COKING METHOD Filed Nov. 25, 1960 UnitedStates Patent 3,151,041 CGKING METHOD Gerald Heinze, Uferstrasse 34,Dortrnund-Schoenau, Germany; Wilhelm Reerink, Meckenstockerweg 112,Essen-Bredeney, Germany; and Heinz Echterhoif, Renatastrasse 1t), Essen,Germany Filed Nov. 25, 1960, Ser. No. 76,086 Claims priority,application Germany, Nov 28, 1959, B 55,716; B 55,717 Claims. (Cl.202-33) The present invention relates to a coking method andparticularly to a method according to which a mixture of carbonaceousbriquettes and fine coal are coked together. Depending on thecomposition of the above mixture, particularly depending on the type andquality of fines forming a constituent of the mixture, the result of thecoking process of the present invention will be either a separablemixture of the coked briquettes and of coke breeze formed of the finesconstituent, or coked bodes wherein each individual coked body willconsist of portions of relatively high density and of portions ofrelatively low density which are integral with each other, as will beexplained in more detail further below.

In the past it has been proposed to produce coke briquettes bybriquetting a granulated low temperature coke mixed with hard coal ofhigh baking properties, and coking the thus-formed briquettes. Or, ithas also been proposed to mix coke produced from non-baking coal withcoking hard coal and tar and to form briquettes of this mixture prior tocoking of the same. It has also been suggested to form mixtures ofgranulated coke and granulated hard coal, to briquette the mixture withor without the addition of pitch or tar and to subject the thus-formedbriquettes to coking. It is furthermore known to form a mixture of cokeand baking or coking hard coal, to add tar and a small quantity of waterderived from low temperature carbonization thereto, thereafter tobriquette and then to coke the mixture. According to anotherproposition, pitch or tar is used as binder for a mixture consisting ofde-gassed non-coking coal and coking hard coal.

The coking of briquettes which were thus produced in various manner hasbeen carried out in accordance with several processes known in the artas the Phurnacite, Carmaux, Brennstofftechnik, Krupp-Lurgi,Lurgi-Spuelgas, Didier and Otto Processes. Furthermore, the coking ofthe briquettes can also be carried out in vertical coking chambers.However, it would be most desirable to be able to produce cokedbriquettes in conventional horizontal by-product ovens which are readilyavailable and which would not require any special apparatus. Experimentsto produce coke briquettes in horizontal byproducts ovens did notsucceed, however, due to the fact that the briquettes were bakedtogether during the coking process or were even molten together to suchan extent that a mass was formed which stuck to the oven walls or tendedto lock in the oven so that removal of the coked charge by pushing thesame out of the oven became impossible.

Referring now to another problem which is solved according to thepresent invention, methods are known according to which it is possibleto produce coke bodies of low or high density as desired. In thesemethods it is always attempted to produce coke of a definite densitywhich varies only within relatively narrow limits. For instance regularblast furnace coke has a density of between 0.7 and 0.9 while foundrycoke preferably has a density of between 0.9 and 1.1. Furthermore, thereexists a variety of special purpose cokes which possess a density ofbetween about 1.3 and 1.5. The term density is meant herein to denoteapparent density.

Patented Siept. 29, 1964 However, as will be discussed further belowthere appears to be a definite need for a coke product wherein eachindividual coke body will include, integral with each other, portions ofrelatively high and portions of relatively low apparent density.

It is therefore an object of the present invention to overcome theaforementioned difficulties in the produc tion of briquetted coke.

It is another object of the present invention to provide a methodaccording to which coke briquettes can be produced in a simple andeconomical manner, for instance in a horizontal by-product oven.

It is a further object of the present invention to provide a method forproducing coke bodies each of which will consist of portions ofrelatively high and portions of relatively low density.

It is yet another object of the present nvention to provide a simple andeconomical method for producing coke of controlled density, shape andcomposition.

Other objects and advantages of the present invention will becomeapparent from a further reading of the description and of the appendedclaims.

With the above and other objects in view, the present inventioncontemplates a method of producing coke briquettes, comprising the stepsof forming a mixture of carbonaceous briquettes which are adapted to becoked without melting together when heated under exclusion of air tobetween 500 and 1300 C. and of low coking fines; coking said mixture soas to transform the briquettes and the fines into coke bodies adheringto each other but slightly; and separating the thus-formed briquettesfrom the coked fines so as to obtain coke breeze in addition to andseparated from the coke briquettes.

However, it is also within the scope of the present invention to providea method of producing coke bodies of varying density, comprising thesteps of forming a mixture of carbonaceous briquettes which are adaptedto be coked without melting together when heated under exclusion of airto be between 500 and 1300" C. and of strongly coking bituminous fines,and coking the mixture so as to transform the briquettes and thebituminous fines into coherent coked bodies each of which includingportions of relatively high density and integral therewith portions ofrelatively low density.

It has been found that according to the present invention it is nowpossible to produce coke briquettes in any coking installation includinghorizontal by-product ovens by forming a mixture of fines and of suchcarbonaceous briquettes which when coked alone will at mostsuperficially melt together. The mixture is then coked in conventionalmanner and after completion of the coking process, the thus-formed cokebriquettes are separated from the coke formed of the fines. Suchseparation can be carried out with relatively mild mechanical means, andthe success of the process depends primarily on the proper choosing ofthe ingredients of the mixture, i.e., on the composition of thebriquettes and of the fines, particularly on the properties andcomposition of the fines.

It has been proposed previously to produce a dense blast furnace cokefrom coal which can be: coked only with difficulties, by coking suchcoals which contain a high proportion of volatile constituents in amixture with briquettes made of the same type of coal. The essentialdifference between the method of the present invention and this priorproposition is that according to the prior art only a uniform mass ofdense blast furnace coke is obtained, while according to the presentinvention on the one hand coke briquettes and on the other hand regularcoke breeze is produced. According to the prior art process, the shapeof the initial briquettes is no longer a? recognizable in the finishedcoke product since the components of the mixture of the prior artprocess will completely melt together during the coking of the same.

Surprisingly, applicants have found that it is possible to coke amixture of briquetted coal and of fines at a temperature preferablybetween 800 and 1300 C., without causing a melting together of the twocomponents of the mixture and without causing a caking together of theentire coke in the coke oven. 7 Thereby it is furthermore achieved thatthe coke briquettes which are formed during the process of the presentinvention are substantially of the same size and shape as the briquetteswhich form one constituent of the mixture which is subjected to coking.The slight difference in size and shape of the finished coke briquettesis due to a slight shrinkage caused by the escape of volatileconstituents. A slight baking together of the briquettes and of thesurrounding coke which has been formed of the fines does not cause anydifliculties and in fact is desirable because it facilitates the pushingout of the coke from the coke oven. Very slight mechanical stress, forinstance dressing by passing through a screening device generally willsuifice for separating the coke mixture into coke briquettes and cokebreeze. If necessary, this separation can be carried out by passing themass leaving the coke oven through a coarse grinding impact grinder.

The choice of suitable fines and briquettes will primarily be determinedby the coking properties of these ingredients. Preferably, thebriquettes which are to be subjected to the above described cokingprocess should be formed of non-coking coal, oxidized coal or even ofcoke. Only slightlyjbakingcoal may also be used or a mixture ofnon-baking coal with slightly or considerably baking or coking coals maybe used as the material for forming the briquettes. Thus, the briquetteswhich are used according to the above described process may be formed ofanthracite and lean coals of up to 14% volatile constituents or of coalsrich in volatile constituents, preferably open-burning coals with morethan 40% volatile constituents. The briquettes may also be formed ofshort-flaming or sernibituminous coal with between 14 and 18%v volatileconstituents provided that such 'coal is only slightly coking or, ifnot, mixed with other slightly ornot at all coking coals.

Thus, substantially all carbonaceous or coal briquettes, even thosecontaining coke, may be used as discussed above, provided that uponheating of suchbbriquettes under the exclusion of air to a temperatureof between 500 and 1300 .C., the briquettes will not melt together. Thebriquettes which are to be coked according to the present invention maycontain any desired binding agent, including water solublebindingagents.

The second constituent of the mixture which is to be coked according tothe present invention, i.e., the fines which preferably willpossessaparticle size of up to 20 generally will be chosen from coking orslightly coking hard coals with between 14% and preferably between 18%and 25% or 28% volatile constituents, since a mixture of such fines withthe above described briquettes will cause formation of a coherent Cokecake which can be easily pressed out of thisoven and which, on the otherhand can be easily separated into coke briquettes and coke breeze.Particularly the combination of such fines with briquettes which whencoked alone WillLnotmelt together, and the coking of such mixture in ahorizontalby-product oven will give the desired result in a very simpleand economical jmanner. However, when the briquettes which are 'to becoked formed of slightly coking coal or contain a high proportion ofpitch or'tar, particular care has to be taken in choosing the fine hardcoal in order to avoid a mixture which upon coking will possess toostrong an adherence between briquette and fines thus making theseparation of the coke briquettes from the coke breeze unnecessarilydiificult. It is therefore desirable to pre-test the fines which are 22to be admixed to the briquettes prior to coking of the thus-formedmixture in order to determine whether the desired result, namely a cakewhich is easily separable into coke briquettes and coke breeze will beobtained thereby. Anthracite and open burning gas coals should not beused as fines.

The following test has been found to determine accurately thesuitability of given fines.

TEST I Cylindrical briquettes are produced of coal and tar, each havinga diameter of about mm. and a height of between about 40 and 50mm. Thesebriquettes are inserted into a crucible made of heat resistant sheetmetal and having an inner diameter which is slightly greater than thediameter of the briquettes. The height of the crucible is about mm.

The fines which are to be tested are then poured onto the briquette inthe crucible. These fines may be a mixture of fines of differentqualities. The crucible is filled in this manner nearly to but notcompletely to its upper rim in such a manner that the upper face of thelayer of fines will be about 1 cm. below the upper rim of the crucible.The cover is then placed On the crucible and the same is embedded in amass of pulverulent coke having a particular size of less than 5 mm.located in a considerably larger crucible. The larger crucible with thesmaller crucible therein is now placed into an electrically heatedfurnace and heated therein to a temperature of 1000 C. in such a mannerthat the increase in the temperature equals about 1 C. per minute.Thereafter, the crucibles and the contents thereof are allowed to cooland the coke formed in this manner is then tested as follows:

When it is possible to separate the coke formed of the layer of fineswithout difiiculties from the coked briquette, then the fines or finesmixture are suitable for use in the present method of simultaneouslyproducing coke briquettes and coke breeze. In the opposite case, i.e.,when the coke formed of the fines is not easily and without applicationof substantial force separated from the coke briquette, then it will benecessary to use less-coking fines or to mix coke breeze to the fines orto otherwise reduce the coking characteristics of the mixture of'fines,until repetition of the above described test gives the desired result.

The granulation of the fines depends to some extent on the size of 'thebriquettes with which the fines are to be mixed. In order to obtain bestutilization of the coke oven space, the particle size of the fines willbe up to about 5 mm. when the same is to be coked together withcommercial egg-shaped briquettes having diameters of between about 50and 80 mm. With increasing size of the briquettes, it is also possibleto use fines of larger particle size or fines containing a largerpercentage of particles of larger size. On the other hand, withdiminishing size of the briquettes it is also desirable to use fines ofrelatively small particle size.

As indicated above, the size of the fines particles is adjusted to thesize of the briquettes primarily in order to obtain best possibleutilization of the coke oven. By suitably correlating the particle sizeof the fines to the size of the briquettes, a substantially completefilling of the .interspaces between the briquettes with fines particleswill be achieved. The foregoing, however, is not to be understood as alimitation of the present invention to specific sizes or sizerelationships of briquetes and fines. It is also possible to form amixture of briquetes of varying sizes and of fines of varying particlesizes and composition and to coke the thus-formed mixture in accordancewith the present invention.

It is preferred according to the present invention to fill theinterspaces between the briquettes by first intro- ,ducingthe briquettesinto the coke'oven and thereafter allowing the fines to flow or tricklethrough the inter plus about 8% spaces of the mass of briquettes. It isalso possible to form in similar manner the mixture of briquettes andfines in a hopper rather than in the coke oven and to introduce thecompleted mixture of briquettes and fines into the coke oven. If ascoking oven a horizontal by product oven is to be used, then the hopperor the like may be adapted to serve as hopper car for introducing themixture into the coke oven. When the coking is to be carried out in acontinuously operating vertical coking chamber, then it is preferred torefill or fill up the coking chamber by first introducing briquettes andthereafter to allow the fines to flow downwardly through the interspacesbetween the individual briquettes.

According to the above described preferred manner of carrying out thepresent invention, namely by first forming a mass of briquettes and thenallowing the fines to trickle through the interspaces between theindividual briquettes of the mass, the coked end product will be easilydivided into briquetted coke and coke breeze. The coke breeze generallycan be separated from the briquettes without using special mechanicalforce, simply by passing the mass over a screen of suitable mesh widthso that the briquettes will not fall through the openings in the screen.When relatively larger quantities of fines are mixed with briquettes sothat the volume of the fines is more than the volume required forfilling the interspaces between the individual briquettes of the mass,then a somewhat coarser coke is obtained in addition to the cokebriquettes. However, even in such case, it is very simple to separatethe briquettes from the remaining coke and to reduce the particle sizeof the remaining coke. It is therefore desirable to choose fines whichwill give a relatively soft coke or a coke which can be easily broken upinto smaller particles.

It is a particular advantage of the above described method of thepresent invention that it is possible in accordance therewith to producecoke briquettes in horizontal by-product ovens which are much morefrequently available than vertical coking chambers of which onlyrelatively few are in operation.

Thus, according to the present invention existing installations can beused in order to supply the increasing demand for coke briquettes.Briquetted coke or coke briquettes can be advantageously used for manypurposes, for instance in shaft lime kilns, cupola furnaces and blastfurnaces. There is particularly great demand for coke briquettescontaining between 1 and or preferably between 2 and 6% of volatileconstituents since such not completely de-gassed coke briquettes arealso eminently suitable for home heating purposes. The desiredincomplete coking is accomplished without difficulty either by reducingthe coking time or by reducing the coking temperature to between 500 and900 C.

The simultaneous production of coke breeze, in addi tion to the cokebriquettes is a further important advantage of the new method. Such cokebreeze with particle sizes of up to about 10 mm. are obtained only inrelatively small quantities, up to about 5% in the conventional cokingof hard coal. However, the demand for coke breeze is steadily increasingfor various industrial uses for instance in the cement industry or invarious sinter methods of ore dressing. It is also possible toincorporate the coke breeze into briquettes which are then treated asdescribed above so as to form coke briquettes. In this manner, byrecycling the coke breeze, the only finished product which will beeventually obtained will be coke briquettes.

Good results were obtained by using in accordance with the presentinvention briquettes which were formed of coke plus about 12% tar;anthracite plus about 10% tar; lean coal containing up to about 14%volatile constituents tar; slightly coking bituminous coals containingabout 14%-18% volatile constituents plus about 5% tar; open-burning coalwith more than 40% Volatile 6 constituents plus about 7% tar; or, cokingcoals together with coke or anthracite or the like plus 7% tar.

The second constituent of the mixture which is to be coked as describedabove, namely the fines, preferably will be a coking hard coalcontaining between 14 and 40% or most preferably between 18 and 28% ofvolatile constituents. Anthracite and openburning coals are not wellsuited as the fines constituents for the reason that these last namedcoal types generally will not form a coherent coke cake.

As pointed out further above, when it is desired to form coke briquetteson the one hand and coke breeze on the other hand, the fines should beof a type which will produce a soft, easily comminutable coke and of nottoo strong coking characteristics.

The embodiments of the present invention described hereinabove arefurther illustrated in the following examples, the invention however notbeing limited to the specific details of these examples.

Example 1 Lean coal containing 13% of volatile constituents and having aparticle size of up to 5 mm. is mixed with 7% tar having a softeningpoint of 66 C. (according to Kraemer-Sarnow) and the thus formed mixtureis compressed into egg briquettes and placed into a hopper car. Amixture consisting of equal parts of coke breeze having a particle sizeof up to 5 mm. and open burning coal containing 32% of volatileconstituents and also having a particle size of up to 5 mm. is thenadded to the briquettes and allowed to flow into the in'terspacestherebetween so as to substantially fill the same. Approximately 30% ofthe thus formed mixture will be represented by the mixture of cokebreeze and open burning coal and about 70% by weight will be representedby the briquettes. The thus formed mixture is then introduced into thecoke oven and coked therein for 24 hours at 1200 C. Thereafter, the cokecake is pressed out of the oven in any conventional manner, extinguishedand passed over a vibrating screen. Thereby approximately by weight ofcoke briquettes and 40% by weight of coke breeze are obtained.

Example II Coke breeze such as is obtained according to the method ofExample I is compressed together with 12% tar and 3% coal tar oil intoelliptic briquettes and the thus formed briquettes are introduced intothe coke oven. Thereafter, a bituminous coal containing 24% of volatileconstituents and having a particle size of up to 10 mm. is introducedfrom above into the coke oven and allowed to flow down so as to fill theinterstices between the previously introduced briquettes. After cokingfor 20 hours at 1250" C., the thus formed coke cake is pressed out ofthe coke oven in conventional manner, extinguished and passed over avibrating screen. In this manner, ap proximately by weight of cokebriquettes and 35% by weight of coke breeze are obtained.

Example III A mixture consisting of equal parts by weight ofsubbituminous coal containing 14% volatile constituents and anthracitecontaining 6% volatile constituents is pressed with 8% tar into cubeshaving an edge length of 100 mm. The thus formed briquettes are thenmixed with one-half of their weight of a mixture consisting ofanthracite and 30% of coking coal containing 20% volatile constituentswhich mixture has an average par ticle size of between 1 and 8 mm. Uponcoking for 22 hours at 1000 C. a coke cake is obtained which isconventionally removed from the coke oven, extinguished and passed overa vibrating screen. 65 by weight of coke briquettes and 35% by weight ofcoke breeze are thus obtained.

7 Example IV A non-coking open burning coal containing 42% of volatileconstituents is mixed iwth 7% of 50% sulfite waste liquor and 7% of hardpitch having a softening point of 155 C. according to Kraemer-Sarnow andthe mixture is pressed into egg-shaped briquettes. The thus formedbriquettes are mixed with 50% 'of their own weight of a mixtureconsisting of 68% of a non-coking open burning coal and 32% of aslightly coking open burning coal. The entire mixture is coked at 1200C. for 24 hours and then removed from the coke oven and extinguished inconventional manner. After passing the thus formed coke mass over. avibrating screen, the same is separated into about 65% of cokebriquettes and 35% of coke breeze.

Example V A finely ground slightly coking coal having 15% of volatileconstituents is compressed at 3000 atmospheres into cylindrically shapedbriquettes. The thus formed briquettes are then mixed with 50% of theirown weight of a mixture consisting of 50% coke breeze and 50% of acoking coal containing 29% volatile constituents. The thus formedmixture is then coked for 18 hours at 900 C., removed from'the cokeoven, and extinguished and passed over a Vibrating screen. 65% of cokebriquettes and 35% of coke breeze are obtained.

According to another embodiment of the present invention, a coke isproduced the individual pieces of which consist of integral portionssome of which have an apparent density of between about 0.7 and 1.1 andothers of between about 1.1 and 1.5.

This novel type of coke is produced according to the present inventionby coking a mixture of bituminous coal and coal briquettes which whencoked alone would only superficially or not at all melt together. Inthis manner, it is possible according to the present invention to obtainpieces of coke in which the coked coal briquettes are substantiallyunchanged and present in their initial shape, however, after cokingthere will be integral with the coke portion which originated from abriquette also a coke portion which originated from the admixture ofbituminous fines. Thus, the cokes pieces formed in this manner willpossess'for instance a core portion of greater density than the densityof the coke portion surrounding the core. The process can be controlledso that substantially each piece of coke produced thereby consists ofportions of higher and portions of lower apparent density, however, itis also possible depending on the degree of admixture of bituminous coalto the coal briquettes, to obtain a coke which also includes cokebriquettes which are free of the-adherence of any coke originating fromthe admixture of the bituminous'coal. Similarly, it is not necessarilyso that the briquette portion of the composite coke piece will be foundin the center of the coke piece. It is also possible that such briquettecoke portion is only partially covered with coke originating frombituminous coal portion.

In order to determine whether given fines when coked together with coalbriquettes will give the desired result, namely coke pieces whichpossess portions of higher and portions of lower apparent density whichportions are integral with each other, it has been found advantageous tocarry out tests such as Test 1 described further above.

This coke formed according to Test I should then be tested to determinewhether the fines which had been poured'on top of the briquettes arefirmly baked to the briquette andalso whether shrinkage cracks continuefrom the fines portion directly into the briquette andvice versa. Ifthis is the case,'then it can be assumed that the fines will give thedesired result in large-scale coking operations. However, in order tofurther test this feature, it is suggested to drop the coke 'piece whichhas been formed in the inner crucible and which consists of fines and-ofthe briquette from a height of about 2 ml onto a steel plate. The cokepiece will break and examination of the inner surfaces exposed by suchfracture of the entire coke piece should show that these fracturesurfaces are not identical with the initial boundary surface between thebriquette and the fines. The surface exposed by fracture of the cokeblock should run at an angle to the initial boundary face. In thismanner, it can be easily determined that the coke formed of thebriquette and the coke formed of the fines have been firmly bound toeach other so as to form an'integral coke body comprising portions thedensity of which is controlled by the properties of the coked briquetteand portions the density of which is controlled by the properties of thecoked fines. If the desired result is not achieved in such tests, thenit will become necessary to suitably change the composition of thefines, primarily in the direction of increasing the coking propertiesthereof.

The dimension of the coal briquettes which form part of the mixturewhich is subjected to coking according to the present invention willdepend on the dimensions of the coke oven and-also on the required sizeof the finally obtained coke pieces. Thus, briquettes of the size ofconventional egg briquettes, i.e., having diameters of between about 50and mrn., may be used or also smaller briquettes, for instance suchhavingdiameters of between 20 and 50 mm., or also largerbriquet-teswhich have diameters greater than 80 mm.

Obviously, the present invention is not limited to the use of briquettesof any given size or of fines of any given particle size. It is alsopossible to coke in accordance with the last discussed embodiment of thepresent invention mixtures of briquettes and fines wherein briquettesand/ or fines include pieces of varying dimensions.

The proportion of briquettes in the mixture which is to be cokedaccording to the last discussed embodiment of the present invention willdepend on the final use of the thus produced coke. For instance, for useas blast furnace coke it will be advantageous to use between about 5 and30% by weight of briquettes mixed with between and 70% of fines. On theother hand, for use in cupola furnaces, preferably between 30 and 50% byweight of briquettes will be mixed with between 70 and 50% by weight-offines.

It has been suggested previously to operate blast furnaces and cupolafurnaces with mixtures of coke briquettes and ordinary coke and tointroduce such mixtures into the respective furnaces, whereby, however,the briquettes and the ordinary particulate coke had to be producedseparately in accordance with conventional methods. In contrast thereto,according to the present invention, it is now possible to produce cokepieces of varying density and to introduce a single material into thefurnace which will contain substantially in each individual piecethereof a portion of coked briquette and of coked fines, i.e., portionsof varying density. This represents a considerable technological advanceand greatly facilitates the operation of the furnace. It is a furtheradvantage of the last discussed embodiment of the present invention thata single coke oven will sufiice to produce the entire coke for thefurnace operation while according toconven-tional methods two types ofcoke ovens will be required since itis not possible to coke briquettesper se in the conventional horizontal by-product ovens. 7' Generally,for coking briquettes it is necessary to resort to vertical cokingchambers of which only relatively few are available while in contrastthereto, horizontal byproduct ovens can be found in many installations.These horizontal by-product ovens are entirely sufiicient for producingthe coke of varying density according to the present invention.

The present invention will also serve to solve the problem of usingnon-coking'or'only slightly coking coals in the production'of coke.Furthermore, thelast discussed embodiment will also permit toincorporate the relatively'low coking constituents into the briquettesand thereby to retain only high cooking fines for the fines portion ofthe coking mixture. By proceeding in this manner, a greater proportionof low coking or non-coking coal can be introduced into the coke oventhan was hereto possible.

The zones or portions of varying apparent density in the individual cokepieces produced according to the last discussed embodiment of thepresent invention are immediately apparent for instance inmicrophotographs of polished coke surfaces made of coke pieces producedas described hereinabove. For instance, it may be seen that therelatively dense portion of the coke piece which originated from thebriquette will have a relatively low volume such as about 30% and ahigher apparent density of about 1.4 while integral therewith anddirectly adjacent thereto, portions will be found which originated fromthe fines and which possess a pore volume of about 50% and acorresponding low apparent density of about 0.9.

The following examples will serve to further illustrate the lastdiscussed embodiment of the present invention without however, limitingthe invention to the specific details of the examples.

Example VI Lean coal containing about 13% of volatile constituents iscompressed into nut-sized briquettes and is then mixed with 4 times itsown weight of coking fines containing 20% of volatile constituents. Thethus formed mixture is then coked for 24 hours at 1250 C. and thereafterremoved from the coke oven and extinguished in conventional manner. Thethus produced coke pieces will consist of portions having an apparentdensity of 0.7 to 0.9 and integral therewith of portions having anapparent density of between 1.3 and 1.5.

Example VII A mixture consisting of 78% lean coal containing 12%volatile constituents, 15% fat coal containing 22% volatile constituentsand 7% tar is compressed into egg briquettes and then mixed with 6 timesits weight of fat coal containing 26% volatile constituents. The thusformed mixture is then poured into a coking chamber and is coked for 24hours at a temperature of 1000 C. The coke pieces resulting therefromare similar to those obtained according to Example VI.

Example VIII Anthracite containing 8% volatile constituents is mixedwith 10% tar and then compressed into egg briquettes. The thus formedbriquettes are then mixed with twice their own weight of a highly cokingcoal containing 27% of volatile constituents. The thus formed mixture isthen introduced into the coke oven and coked for 24 hours at 1150 C. Thecoke pieces obtained therefrom possess integral portions of varyingdensity and are particularly suitable for use in the operation of cupolafurnaces.

Example IX Finely ground fat coal containing 22% volatile constituentsis compressed at a pressure of 3000 atmospheres into cylindricalbriquettes and the thus formed briquettes are then mixed with timestheir own weight of fat fines containing 26% of volatile constituents.The mixture is coked for 22 hours at a temperature of 1150 C. and itwill be found that the resulting coke pieces possess integral portionsof varying density substantially like those described in connection withExample VI.

The drawing shows a microphotograph of a piece of coke produced inaccordance with Example VI. The areas of greater and lesser density arereadily apparent.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. A method of producing coke briquettes, comprising the steps offorming a mixture of carbonaceous briquettes which are adapted to becoked without melting together when heated under exclusion of air tobetween 500 and 1300 C. and of low baking fine hard coal; coking saidmixture so as to transform said briquettes and said fines into cokebodies adhering to each other but. slightly; and separating thethus-formed coked briquettes from the coked fines so as to obtain cokedbreeze in addition to and separated from said coke briquettes.

2. A method of producing coke briquettes, comprising the steps offorming a mixture of binder-containing coal briquettes which are adaptedto be coked without melting together when heated under exclusion of airto between 500" and 1300 C. and of low baking fine hard coal; cokingsaid mixture so as to transform said briquettes and said fines into cokebodies adhering to each other but slightly; and mechanically separatingthe thus forming coked briquettes from the coked fines so as to obtaincoke breeze in addition to and separated from said coke briquettes.

3. A method of producing coke briquettes, comprising the steps offorming a mixture of carbonaceous briquettes which are adapted to becoked without melting together when heated under exclusion of air tobetween 500 and 1300 C. and of low baking fine fat coal containingbetween 18 and 28 percent of volatile constituents; coking said mixtureso as to transform said briquettes and said fines into coke bodiesadhering to each other but slightly; and separating the thus-formedcoked briquettes from the coked fines so as to obtain coke breeze inaddition to and separated from said coke briquettes.

4. A method of producing coke briquettes, comprising the steps ofembedding in a horizontal by-product oven coal briquettes which areadapted to be coked without melting together when heated under exclusionof air to between 500 and 1300 C. in low baking fine hard coal; cokingsaid mixture so as to transform said briquettes and said fines into cokebodies adhering to each other but slightly; and mechanically separatingthe thus-formed coked briquettes from the coked fines so as to obtaincoke breeze in addition to and separated from said coke briquettes.

5. A method of producing coke briquettes, comprising the steps offorming a mixture of carbonaceous briquettes which are adapted to becoked Without melting together when heated under exclusion of air tobetween 500 and 1300 C. and of low baking fine hard coal, the quantityof said fines being so chosen as to be substantially sufiicient to fillthe interstices between said cabonaceous briquettes; coking said mixtureso as to transform said briquettes and said fines into coke bodiesadhering to each other but slightly; and separating the thus-formedcoked briquettes from the coked fines so as to obtain coke breeze inaddition to and separated from said coke briquettes.

6. A method of producing coke bodies of varying density, comprising thesteps of forming a mixture of carbonaceous briquettes which are adaptedto be coked without melting together when heated under exclusion of airto'be between 500 and 1300 C. and of strongly baking bituminous fines;and coking said mixture so as to transform said briquettes and saidbituminous fines into coherent coked bodies each of which includingportions of relatively high density and integral therewith portions ofrelatively low density.

7. A method of producing coke bodies of varying density, comprising thesteps of forming a mixture of carbonaceous briquettes which are adaptedto be coked without melting together when heated under exclusion of airto be between 500* and 1300 C. and of strongly baking bituminous fines;colgingsaid mixture so as to transform said briquettes and saidbituminous fines into a coked body including portions of relatively highdensity and integral therewith portions of relatively low density; andsubdividing said coked body so as to obtain a plurality of smaller cokedbodies substantially each of which comprises integral portions ofrelatively high and relatively low density.

8. A method of producing coke bodies of varying density adapted for usein blast furnace operations, compriswhich are adapted to be cokedwithout melting together and 5 percent by weight of carbonaceousbriquettes which are adapted to be coked without melting together whenheated under exclusion of air to be between 500 and 1300 C. and ofbetween about 70 and 95 percent by weight of strongly baking bituminousfines; and coking said mixture soas to transform said briquettes andsaid bituminous fines into coherent coked bodies each of which includingportions of relatively high density and integral therewithv portions .ofrelatively low density.

9. A method of producing coke bodies of varying density adapted for usein cupola furnace operation, comprising the steps of forming a mixtureofbetween about and percent by weight of carbonaceous briquettes whichare adapted to be col zed without meling together when heated underexclusion of air to be between 500 and 1300 C. and of between about and50 percent by weight of strongly bakingbituminous fines; and coking saidmixture so as to transform said briquettes and said bituminous finesinto coherent coked bodies each of which including portions ofrelatively high density and integral therewith portions of relativelylow density.

10. A method of producing coke, comprising the steps of forming amixture of carbonaceous briquettes which are adapted to be coked withoutmelting together when heated under exclusionof air to between 5 00 and1300 C., and of fine hard coal; and coking the. thus, formed mixture soas to transform said briquettes and said coal into coke.

References Cited in the file of this patent UNITED STATES PATENTS1,824,526 Andrews Sept. 22, 1931 2,353,753 Otto u July 18, 19442,600,078 Schutte et a1 June 10, 1952 2,907,698 Schulz Oct. 6, 1 959FOREIGN PATENTS 389,066 Great Britain June 2, 193]

6. A METHOD OF PRODUCING COKE BODIES OF VARYING DENSITY, COMPRISING THESTEPS OF FORMING A MIXTURE OF CARBONACEOUS BRIQUETTES WHICH ARE ADAPTEDTO BE COKED WITHOUT MELTING TOGETHER WHEN HEATED UNDER EXCLUSION OF AIRTO BE BETWEEN 500* AND 1300*C. AND OF STRONGLY BAKING BITUMINOUS FINES;AND COKING SAID MIXTURE SO AS TO TRANSFORM SAID BRIQUETTES AND SAIDBITUMINOUS FINES INTO